On the first 5 tests of her language class, Tiffany got an average score of 82. What does she need on the next test to have an overall average of 84?
Answer: Let her score on the next test be $x$ The sum of all of her scores is then $5 \cdot 82 + x$ The same sum must also be equal to $6 \cdot 84$ Solve: $x = 6 \cdot 84 - 5 \cdot 82 = 94$.